1. Field of the Invention
The present invention relates to a page data processor converting page data described in a page data description language to data of a format output-processible by an output device.
2. Description of the Background Art
In the field of printing/prepress, an image processor generally performs rasterization (RIP processing) on page data described in a page description language (hereinafter abbreviated as PDL) represented by PostScript (trade name by Adobe Systems Inc., U.S.A.) or PDF (portable document format) for generating output data and outputs page contents expressed by the page data to a recording medium such as a film, a printing plate or a paper through an output unit such as an image setter, a plate writer or a digital printing machine.
Such page data is generally formed to be separable into a plurality of separation data. The term “separation data” denotes data of specific colors employed in the aforementioned printing, and is also simply referred to as “separation”. The verb “separate” denotes operation of obtaining separation data from the page data. Rasterization processing is performed for generating a plurality of rasterized separation data corresponding to some separations. The output unit performs output processing every color on the basis of the rasterized separation data, thereby performing color printing on the basis of the page data.
Two types of methods, i.e., consecutive RIP processing and at-a-time RIP processing are present as rasterization processing methods for generating such a plurality of rasterized separation data. In the consecutive RIP processing, separation and rasterization processing are consecutively performed every separation data for sequentially generating a plurality of rasterized separation data one by one. In the at-a-time RIP processing, rasterization processing is performed at a time on the overall page data for simultaneously generating a plurality of rasterized separation data.
In the consecutive RIP processing, the first one of the plurality of rasterized separation data can be precedently generated. However, a time corresponding to the number of separation data separated from the page data is required for creating all rasterized separation data due to the rasterization processing consecutively performed on the respective separation data.
In the at-a-time RIP processing, generation of all rasterized separation data ends earlier than that in the consecutive RIP processing. However, it is impossible to output only rasterized separation data corresponding to specific emergently required separation data such as the first one of the rasterized separation data due to collective creation of all rasterized separation data.
In consideration of such characteristics, an operator selects either rasterization processing as the need arises.
When the output unit is connected to a rasterization processor rasterizing the page data and the rasterized separation data are directly transmitted to the output unit, either the consecutive RIP processing or the at-a-time RIP processing must be selected in consideration of improvement in efficiency of printing/prepress steps. In other words, improvement in efficiency must be taken into consideration as to not only the rasterization processor but also output operation in the output unit.
That is, there are rasterized separation data requiring a long time for output processing in the output unit as well as rasterized separation data completely output in a short time. When output processing in the output unit ends in a short time, there is a high possibility for a time when the output unit is not in operation, i.e., a non-operating time, and hence it follows that the operation efficiency of the output unit is reduced.
The rasterization processing method in the rasterization processor must be selected also in consideration of this, and this selection process applies an excessive burden on the operator.